You can permanently delete a flowflow - A flow represents the full lifecycle of a call. It is a road map to how calls will be handled from the moment they enter the phone system to the end of the call. provided there are no numbers assigned to it:

1. Select the Admin tab [1] and click Studio [2].
2. Click on the More Options icon [⋯] of the flow you wish to delete [3].
3. Click on Delete flow [4].

4. When the dialog appears, hit Delete flow to confirm your action [5].